151
|
Hladky SB, Barrand MA. The glymphatic hypothesis: the theory and the evidence. Fluids Barriers CNS 2022; 19:9. [PMID: 35115036 PMCID: PMC8815211 DOI: 10.1186/s12987-021-00282-z] [Citation(s) in RCA: 87] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 10/15/2021] [Indexed: 12/13/2022] Open
Abstract
The glymphatic hypothesis proposes a mechanism for extravascular transport into and out of the brain of hydrophilic solutes unable to cross the blood-brain barrier. It suggests that there is a circulation of fluid carrying solutes inwards via periarterial routes, through the interstitium and outwards via perivenous routes. This review critically analyses the evidence surrounding the mechanisms involved in each of these stages. There is good evidence that both influx and efflux of solutes occur along periarterial routes but no evidence that the principal route of outflow is perivenous. Furthermore, periarterial inflow of fluid is unlikely to be adequate to provide the outflow that would be needed to account for solute efflux. A tenet of the hypothesis is that flow sweeps solutes through the parenchyma. However, the velocity of any possible circulatory flow within the interstitium is too small compared to diffusion to provide effective solute movement. By comparison the earlier classical hypothesis describing extravascular transport proposed fluid entry into the parenchyma across the blood-brain barrier, solute movements within the parenchyma by diffusion, and solute efflux partly by diffusion near brain surfaces and partly carried by flow along "preferred routes" including perivascular spaces, white matter tracts and subependymal spaces. It did not suggest fluid entry via periarterial routes. Evidence is still incomplete concerning the routes and fate of solutes leaving the brain. A large proportion of the solutes eliminated from the parenchyma go to lymph nodes before reaching blood but the proportions delivered directly to lymph or indirectly via CSF which then enters lymph are as yet unclear. In addition, still not understood is why and how the absence of AQP4 which is normally highly expressed on glial endfeet lining periarterial and perivenous routes reduces rates of solute elimination from the parenchyma and of solute delivery to it from remote sites of injection. Neither the glymphatic hypothesis nor the earlier classical hypothesis adequately explain how solutes and fluid move into, through and out of the brain parenchyma. Features of a more complete description are discussed. All aspects of extravascular transport require further study.
Collapse
Affiliation(s)
- Stephen B. Hladky
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD UK
| | - Margery A. Barrand
- Department of Pharmacology, University of Cambridge, Cambridge, CB2 1PD UK
| |
Collapse
|
152
|
Li J, Zhang X, Guo J, Yu C, Yang J. Molecular Mechanisms and Risk Factors for the Pathogenesis of Hydrocephalus. Front Genet 2022; 12:777926. [PMID: 35047005 PMCID: PMC8762052 DOI: 10.3389/fgene.2021.777926] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 12/03/2021] [Indexed: 12/22/2022] Open
Abstract
Hydrocephalus is a neurological condition due to the aberrant circulation and/or obstruction of cerebrospinal fluid (CSF) flow with consequent enlargement of cerebral ventricular cavities. However, it is noticed that a lot of patients may still go through symptomatic progression despite standard shunting procedures, suggesting that hydrocephalus is far more complicated than a simple CSF circulative/obstructive disorder. Growing evidence indicates that genetic factors play a fundamental role in the pathogenesis of some hydrocephalus. Although the genetic research of hydrocephalus in humans is limited, many genetic loci of hydrocephalus have been defined in animal models. In general, the molecular abnormalities involved in the pathogenesis of hydrocephalus include brain development and ependymal cell dysfunction, apoptosis, inflammation, free radical generation, blood flow, and cerebral metabolism. Moreover, recent studies have indicated that the molecular abnormalities relevant to aberrant cerebral glymphatic drainage turn into an attractive subject in the CSF circulation disorder. Furthermore, the prevalent risk factors could facilitate the development of hydrocephalus. In this review, we elicited some possible fundamental molecular mechanisms and facilitating risk factors involved in the pathogenesis of hydrocephalus, and aimed to widen the diagnosis and therapeutic strategies for hydrocephalus management. Such knowledge could be used to improve patient care in different ways, such as early precise diagnosis and effective therapeutic regimens.
Collapse
Affiliation(s)
- Jingwen Li
- Department of Neurosurgery, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Xinjie Zhang
- Department of Neurosurgery, Tianjin Medical University General Hospital, Tianjin, China
| | - Jian Guo
- Department of Neurosurgery, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Chen Yu
- Department of Neurosurgery, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Jun Yang
- Department of Neurosurgery, Xiang'an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| |
Collapse
|
153
|
Mehta NH, Sherbansky J, Kamer AR, Carare RO, Butler T, Rusinek H, Chiang GC, Li Y, Strauss S, Saint-Louis LA, Theise ND, Suss RA, Blennow K, Kaplitt M, de Leon MJ. The Brain-Nose Interface: A Potential Cerebrospinal Fluid Clearance Site in Humans. Front Physiol 2022; 12:769948. [PMID: 35058794 PMCID: PMC8764168 DOI: 10.3389/fphys.2021.769948] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 11/26/2021] [Indexed: 12/17/2022] Open
Abstract
The human brain functions at the center of a network of systems aimed at providing a structural and immunological layer of protection. The cerebrospinal fluid (CSF) maintains a physiological homeostasis that is of paramount importance to proper neurological activity. CSF is largely produced in the choroid plexus where it is continuous with the brain extracellular fluid and circulates through the ventricles. CSF movement through the central nervous system has been extensively explored. Across numerous animal species, the involvement of various drainage pathways in CSF, including arachnoid granulations, cranial nerves, perivascular pathways, and meningeal lymphatics, has been studied. Among these, there is a proposed CSF clearance route spanning the olfactory nerve and exiting the brain at the cribriform plate and entering lymphatics. While this pathway has been demonstrated in multiple animal species, evidence of a similar CSF egress mechanism involving the nasal cavity in humans remains poorly consolidated. This review will synthesize contemporary evidence surrounding CSF clearance at the nose-brain interface, examining across species this anatomical pathway, and its possible significance to human neurodegenerative disease. Our discussion of a bidirectional nasal pathway includes examination of the immune surveillance in the olfactory region protecting the brain. Overall, we expect that an expanded discussion of the brain-nose pathway and interactions with the environment will contribute to an improved understanding of neurodegenerative and infectious diseases, and potentially to novel prevention and treatment considerations.
Collapse
Affiliation(s)
- Neel H. Mehta
- Undergraduate Department of Biology, Cornell University, Ithaca, NY, United States
| | | | - Angela R. Kamer
- Department of Periodontology and Implant Dentistry, NYU College of Dentistry, New York, NY, United States
| | - Roxana O. Carare
- Department of Medicine, University of Southampton, Southampton, United Kingdom
| | - Tracy Butler
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
| | - Henry Rusinek
- Department of Radiology, NYU Langone Health, New York, NY, United States
| | - Gloria C. Chiang
- Department of Radiology, Weill Cornell Medicine, New York, NY, United States
| | - Yi Li
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
| | - Sara Strauss
- Department of Radiology, Weill Cornell Medicine, New York, NY, United States
| | - L. A. Saint-Louis
- Department of Radiology, NYU Langone Health, New York, NY, United States
| | - Neil D. Theise
- Department of Pathology, NYU Grossman School of Medicine, New York, NY, United States
| | - Richard A. Suss
- Division of Neuroradiology, Department of Radiology, University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Kaj Blennow
- Clinical Neurochemistry Lab, Inst. of Neuroscience and Physiology, University of Gothenburg, Sahlgrenska University Hospital, Göteborg, Sweden
| | - Michael Kaplitt
- Laboratory of Molecular Neurosurgery, Department of Neurological Surgery, Weill Cornell Medical College, New York, NY, United States
| | - Mony J. de Leon
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
| |
Collapse
|
154
|
Nutcracker phenomenon with a daily persistent headache as the primary symptom: Case series and a proposed pathogenesis model based on a novel MRI technique to evaluate for spinal epidural venous congestion. J Neurol Sci 2022; 434:120170. [DOI: 10.1016/j.jns.2022.120170] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 12/30/2021] [Accepted: 01/21/2022] [Indexed: 11/20/2022]
|
155
|
Kahraman Ozlu EB, Kayalar AE, Ertan Y. Investigation of the Presence of Arachnoid Granulation in Fetuses and Early Infancy. JOURNAL OF CHILD SCIENCE 2022. [DOI: 10.1055/s-0042-1758451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
AbstractThe aim of our study is to investigate the importance of arachnoid granulation in cerebrospinal fluid physiology in fetuses and early infancy. Using the random sampling method, postmortem fetuses more than 26 weeks of gestation age and the children under the age of 1 year were chosen from the autopsy materials. Two male and two female intrauterine dead fetus; three male and three female, totally six children under the age of 1 year and one 3-year-old male were included in this study. In cases of intrauterine fetuses more than 26 weeks of gestation and children under the age of 1 year, complete invagination of arachnoid villi into the superior sagittal sinus was examined histologically. In the intrauterine period and in the first 6 months of life, arachnoid villi structures were not found in histologic preparations although in preparations taken after the 6 months of life samples showed similarities to arachnoid granulations. These structures were considered as arachnoid villi drafts after immunohistochemical analysis. In the control case who were 3 years old, maturation of arachnoid villi was complete and the arachnoid villi were invaginated into the superior sagittal sinus as fingerlike extensions. In our study, we think that the failure after E3V intervention in the treatment of hydrocephalus in cases under the age of 1 years may be related to the completion of arachnoid granulation development after the 18th month of life and the immature resorption capacity in this period.
Collapse
Affiliation(s)
| | - Ali Erhan Kayalar
- Department of Neurosurgery, Haydarpasa Education and Research Hospital, Uskudar/Istanbul, Turkey
| | - Yesim Ertan
- Department of Pathology, Ege University Faculty of Medicine, Bornova/Izmir, Turkey
| |
Collapse
|
156
|
Szczygielski J, Kopańska M, Wysocka A, Oertel J. Cerebral Microcirculation, Perivascular Unit, and Glymphatic System: Role of Aquaporin-4 as the Gatekeeper for Water Homeostasis. Front Neurol 2021; 12:767470. [PMID: 34966347 PMCID: PMC8710539 DOI: 10.3389/fneur.2021.767470] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/12/2021] [Indexed: 12/13/2022] Open
Abstract
In the past, water homeostasis of the brain was understood as a certain quantitative equilibrium of water content between intravascular, interstitial, and intracellular spaces governed mostly by hydrostatic effects i.e., strictly by physical laws. The recent achievements in molecular bioscience have led to substantial changes in this regard. Some new concepts elaborate the idea that all compartments involved in cerebral fluid homeostasis create a functional continuum with an active and precise regulation of fluid exchange between them rather than only serving as separate fluid receptacles with mere passive diffusion mechanisms, based on hydrostatic pressure. According to these concepts, aquaporin-4 (AQP4) plays the central role in cerebral fluid homeostasis, acting as a water channel protein. The AQP4 not only enables water permeability through the blood-brain barrier but also regulates water exchange between perivascular spaces and the rest of the glymphatic system, described as pan-cerebral fluid pathway interlacing macroscopic cerebrospinal fluid (CSF) spaces with the interstitial fluid of brain tissue. With regards to this, AQP4 makes water shift strongly dependent on active processes including changes in cerebral microcirculation and autoregulation of brain vessels capacity. In this paper, the role of the AQP4 as the gatekeeper, regulating the water exchange between intracellular space, glymphatic system (including the so-called neurovascular units), and intravascular compartment is reviewed. In addition, the new concepts of brain edema as a misbalance in water homeostasis are critically appraised based on the newly described role of AQP4 for fluid permeation. Finally, the relevance of these hypotheses for clinical conditions (including brain trauma and stroke) and for both new and old therapy concepts are analyzed.
Collapse
Affiliation(s)
- Jacek Szczygielski
- Department of Neurosurgery, Institute of Medical Sciences, University of Rzeszów, Rzeszów, Poland.,Department of Neurosurgery, Faculty of Medicine and Saarland University Medical Center, Saarland University, Homburg, Germany
| | - Marta Kopańska
- Department of Pathophysiology, Institute of Medical Sciences, University of Rzeszów, Rzeszów, Poland
| | - Anna Wysocka
- Chair of Internal Medicine and Department of Internal Medicine in Nursing, Faculty of Health Sciences, Medical University of Lublin, Lublin, Poland
| | - Joachim Oertel
- Department of Neurosurgery, Faculty of Medicine and Saarland University Medical Center, Saarland University, Homburg, Germany
| |
Collapse
|
157
|
Cousins O, Hodges A, Schubert J, Veronese M, Turkheimer F, Miyan J, Engelhardt B, Roncaroli F. The Blood‐CSF‐Brain Route of Neurological Disease: The Indirect Pathway into the Brain. Neuropathol Appl Neurobiol 2021; 48:e12789. [DOI: 10.1111/nan.12789] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 12/08/2021] [Accepted: 12/14/2021] [Indexed: 11/26/2022]
Affiliation(s)
- Oliver Cousins
- Department of Neuroimaging, IoPPN, King’s College London London United Kingdom
| | - Angela Hodges
- Department of Old Age Psychiatry, IoPPN, King’s College London London United Kingdom
| | - Julia Schubert
- Department of Neuroimaging, IoPPN, King’s College London London United Kingdom
| | - Mattia Veronese
- Department of Neuroimaging, IoPPN, King’s College London London United Kingdom
| | - Federico Turkheimer
- Department of Neuroimaging, IoPPN, King’s College London London United Kingdom
| | - Jaleel Miyan
- Division of Neuroscience and Experimental Psychology School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, M13 9PL
| | | | - Federico Roncaroli
- Division of Neuroscience and Experimental Psychology School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, M13 9PL
- Geoffrey Jefferson Brain Research Centre; Manchester Academic Health Science Centre Manchester UK
| |
Collapse
|
158
|
Schreiner TG, Popescu BO. Amyloid Beta Dynamics in Biological Fluids-Therapeutic Impact. J Clin Med 2021; 10:5986. [PMID: 34945282 PMCID: PMC8706225 DOI: 10.3390/jcm10245986] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 12/12/2021] [Accepted: 12/16/2021] [Indexed: 12/21/2022] Open
Abstract
Despite the significant impact of Alzheimer's disease (AD) at individual and socioeconomic levels and the numerous research studies carried out on this topic over the last decades, the treatments available in daily clinical practice remain less than satisfactory. Among the accepted etiopathogenic hypotheses, the amyloidogenic pathway theory, although intensively studied and even sometimes controversial, is still providing relevant theoretical elements for understanding the etiology of AD and for the further development of possible therapeutic tools. In this sense, this review aims to offer new insights related to beta amyloid (Aβ), an essential biomarker in AD. First the structure and function of Aβ in normal and pathological conditions are presented in detail, followed by a discussion on the dynamics of Aβ at the level of different biological compartments. There is focus on Aβ elimination modalities at central nervous system (CNS) level, and clearance via the blood-brain barrier seems to play a crucial/dominant role. Finally, different theoretical and already-applied therapeutic approaches for CNS Aβ elimination are presented, including the recent "peripheral sink therapeutic strategy" and "cerebrospinal fluid sinks therapeutic strategy". These data outline the need for a multidisciplinary approach designed to deliver a solution to stimulate Aβ clearance in more direct ways, including from the cerebrospinal fluid level.
Collapse
Affiliation(s)
- Thomas Gabriel Schreiner
- Faculty of Medicine, University of Medicine and Pharmacy “Carol Davila”, 050474 Bucharest, Romania;
- Neurology Department, University of Medicine and Pharmacy “Grigore T. Popa”, 700115 Iași, Romania
- Department of Electrical Measurements and Materials, Faculty of Electrical Engineering and Information Technology, Gheorghe Asachi Technical University of Iasi, 700050 Iasi, Romania
| | - Bogdan Ovidiu Popescu
- Faculty of Medicine, University of Medicine and Pharmacy “Carol Davila”, 050474 Bucharest, Romania;
- Neurology Department, Colentina Clinical Hospital, 020125 Bucharest, Romania
- Laboratory of Cell Biology, Neurosciences and Experimental Myology, ‘Victor Babes’ National Institute of Pathology, 050096 Bucharest, Romania
| |
Collapse
|
159
|
Decker Y, Krämer J, Xin L, Müller A, Scheller A, Fassbender K, Proulx ST. Magnetic resonance imaging of cerebrospinal fluid outflow after low-rate lateral ventricle infusion in mice. JCI Insight 2021; 7:150881. [PMID: 34905509 PMCID: PMC8855808 DOI: 10.1172/jci.insight.150881] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The anatomical routes for the clearance of cerebrospinal fluid (CSF) remain incompletely understood. However, recent evidence has given strong support for routes leading to lymphatic vessels. A current debate centers upon the routes through which CSF can access lymphatics, with evidence emerging for either direct routes to meningeal lymphatics or along cranial nerves to reach lymphatics outside the skull. Here, a method was established to infuse contrast agent into the ventricles using indwelling cannulae during imaging of mice at 2 and 12 months of age by magnetic resonance imaging. As expected, a significant decline in overall CSF turnover was found with aging. Quantifications demonstrated that the bulk of the contrast agent flowed from the ventricles to the subarachnoid space in the basal cisterns. Comparatively little contrast agent signal was found at the dorsal aspect of the skull. The imaging dynamics from the two cohorts revealed that the contrast agent cleared from the cranium through the cribriform plate to the nasopharyngeal lymphatics. On decalcified sections, we confirmed that fluorescentlylabeled ovalbumin drains through the cribriform plate and can be found within lymphatics surrounding the nasopharynx. In conclusion, routes leading to nasopharyngeal lymphatics appear to be a major efflux pathway for cranial CSF.
Collapse
Affiliation(s)
- Yann Decker
- Department of Neurology, Saarland University, Homburg, Germany
| | - Jonas Krämer
- Department of Neurology, Saarland University, Homburg, Germany
| | - Li Xin
- Theodor Kocher Institute, University of Bern, Bern, Switzerland
| | - Andreas Müller
- Clinic for Diagnostic and Interventional Radiology, Saarland University, Homburg, Germany
| | - Anja Scheller
- Department of Physiology, Saarland University, Homburg, Germany
| | | | - Steven T Proulx
- Theodor Kocher Institute, University of Bern, Bern, Switzerland
| |
Collapse
|
160
|
Fame RM, Lehtinen MK. Mitochondria in Early Forebrain Development: From Neurulation to Mid-Corticogenesis. Front Cell Dev Biol 2021; 9:780207. [PMID: 34888312 PMCID: PMC8650308 DOI: 10.3389/fcell.2021.780207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/10/2021] [Indexed: 01/07/2023] Open
Abstract
Function of the mature central nervous system (CNS) requires a substantial proportion of the body’s energy consumption. During development, the CNS anlage must maintain its structure and perform stage-specific functions as it proceeds through discrete developmental stages. While key extrinsic signals and internal transcriptional controls over these processes are well appreciated, metabolic and mitochondrial states are also critical to appropriate forebrain development. Specifically, metabolic state, mitochondrial function, and mitochondrial dynamics/localization play critical roles in neurulation and CNS progenitor specification, progenitor proliferation and survival, neurogenesis, neural migration, and neurite outgrowth and synaptogenesis. With the goal of integrating neurodevelopmental biologists and mitochondrial specialists, this review synthesizes data from disparate models and processes to compile and highlight key roles of mitochondria in the early development of the CNS with specific focus on forebrain development and corticogenesis.
Collapse
Affiliation(s)
- Ryann M Fame
- Department of Pathology, Boston Children's Hospital, Boston, MA, United States
| | - Maria K Lehtinen
- Department of Pathology, Boston Children's Hospital, Boston, MA, United States
| |
Collapse
|
161
|
Leaston J, Kulkarni P, Gharagouzloo C, Qiao J, Bens N, Ferris CF. Do We Swallow the Waste From Our Brain? Front Neurosci 2021; 15:763780. [PMID: 34887724 PMCID: PMC8649892 DOI: 10.3389/fnins.2021.763780] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 10/22/2021] [Indexed: 11/13/2022] Open
Abstract
Ferumoxytol, an iron oxide nanoparticle, was infused into the lateral cerebroventricle of awake rats to follow its movement and clearance from the brain using magnetic resonance imaging. Within minutes the contrast agent could be observed accumulating in the subarachnoid space, nasal cavity, nasal pharynx, and soft palate at the back of the throat. In a subsequent study fluorescent quantum dots were infused into the brain of rats and within 15 min could be observed in the esophagus using microscopy. These imaging studies clearly show that these large nanoparticle tracers (∼20 nm in diameter) leave the brain through the nasal cavity and end up in the gut. There are numerous studies going back decades reporting the clearance of tracers put directly into the brain. While these studies show the slow accumulation of trace in the blood and lymphatics, they report only accounting for less than 50% of what was originally put in the brain.
Collapse
Affiliation(s)
| | - Praveen Kulkarni
- Center for Translational Neuroimaging, Northeastern University, Boston, MA, United States
| | - Codi Gharagouzloo
- Imaginostics, Inc., Cambridge, MA, United States.,Center for Translational Neuroimaging, Northeastern University, Boston, MA, United States
| | - Ju Qiao
- Center for Translational Neuroimaging, Northeastern University, Boston, MA, United States
| | - Nicole Bens
- Center for Translational Neuroimaging, Northeastern University, Boston, MA, United States
| | - Craig F Ferris
- Center for Translational Neuroimaging, Northeastern University, Boston, MA, United States
| |
Collapse
|
162
|
Eide PK, Ringstad G. Cerebrospinal fluid egress to human parasagittal dura and the impact of sleep deprivation. Brain Res 2021; 1772:147669. [PMID: 34587499 DOI: 10.1016/j.brainres.2021.147669] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/26/2021] [Accepted: 09/22/2021] [Indexed: 10/20/2022]
Abstract
Emerging evidence suggests that the glymphatic system and meningeal lymphatic vessels are instrumental for clearance of toxic metabolites from the brain. Animal and human studies suggest that glymphatic circulation is up-regulated during sleep. Meningeal lymphatic clearance may be more efficient in the wake state, as shown in rodents. We have previously shown clearance of cerebrospinal fluid directly from the subarachnoid space to the parasagittal dura, which harbors meningeal lymphatic vessels. Hence, assessing molecular clearance from parasagittal dura provides an opportunity to decipher the role of sleep/sleep deprivation in human lymphatic clearance function. In this study, we applied magnetic resonance imaging to explore whether sleep deprivation modifies molecular clearance from human parasagittal dura, utilizing an intrathecal magnetic resonance imaging contrast agent as tracer. We hypothesized that tracer enhancement in parasagittal dura would differ after sleep deprivation. One group of individuals (n = 7) underwent one night's total sleep deprivation while a control group (n = 9) was allowed unrestricted sleep. There were no sleep restrictions after the 24-hour time point. After one night of sleep deprivation (at 24 h), we found neither evidence for altered tracer enrichment in the parasagittal dura, nor after a day of unrestricted sleep (at 48 h). The hypothesis of altered molecular egress to parasagittal dura after sleep deprivation was not supported by our data. Further studies are required to determine the role of sleep for molecular clearance from cerebrospinal fluid to meningeal lymphatic vessels in humans.
Collapse
Affiliation(s)
- Per Kristian Eide
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway; Department of Neurosurgery, Oslo University Hospital - Rikshospitalet, Oslo, Norway.
| | - Geir Ringstad
- Department of Radiology, Oslo University Hospital - Rikshospitalet, Oslo, Norway.
| |
Collapse
|
163
|
Ma L, He W, Li X, Liu X, Cao H, Guo L, Xiao X, Xu Y, Wu Y. Decreased CSF Dynamics in Treatment-Naive Patients with Essential Hypertension: A Study with Phase-Contrast Cine MR Imaging. AJNR Am J Neuroradiol 2021; 42:2146-2151. [PMID: 34620585 DOI: 10.3174/ajnr.a7284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 08/05/2021] [Indexed: 12/28/2022]
Abstract
BACKGROUND AND PURPOSE Arterial sclerosis resulting from hypertension slows CSF transportation in the perivascular spaces, showing the intrinsic relationship between the CSF and the blood vasculature. However, the exact effect of hypertension on human CSF flow dynamics remains unclear. The present study aimed to evaluate CSF flow dynamics in treatment-naive patients with essential hypertension using phase-contrast cine MR imaging. MATERIALS AND METHODS The study included 60 never-treated patients with essential hypertension and 60 subjects without symptomatic atherosclerosis. CSF flow parameters, such as forward flow volume, forward peak velocity, reverse flow volume, reverse peak velocity, average flow, and net flow volume, were measured with phase-contrast cine MR imaging. Differences between the 2 groups were assessed to determine the independent determinants of these CSF flow parameters. RESULTS Forward flow volume, forward peak velocity, reverse flow volume, reverse peak velocity, and average flow in the patients with hypertension significantly decreased (all, P < .05). Increasing systolic blood pressure was significantly associated with lower forward flow volume (β = -0.44 mL/mL/mm Hg; 95% CI, -0.83 to -0.06 mL/mL/mm Hg), forward peak velocity (β = -0.50 cm/s/mm Hg; 95% CI, -0.88 to -0.12 cm/s/mm Hg), reverse flow volume (β = -0.61 mL/mL/mm Hg; 95% CI, -0.97 to -0.26 mL/mL/mm Hg), reverse peak velocity (β = -0.55 cm/s/mm Hg; 95% CI, -0.91-0.18 cm/s/mm Hg), and average flow (β = -0.50 mL/min/mm Hg; 95% CI, -0.93 to -0.08 mL/min/mm Hg). CONCLUSIONS The CSF flow dynamics in patients with hypertension are decreased, and increasing systolic blood pressure is strongly associated with lower CSF flow dynamics.
Collapse
Affiliation(s)
- L Ma
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - W He
- Department of Radiology (W.H.), Guangdong 999 Brain Hospital, Guangzhou, China
| | - X Li
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - X Liu
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - H Cao
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - L Guo
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - X Xiao
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Y Xu
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Y Wu
- From the Department of Medical Imaging (L.M., X. Li, X. Liu, H.C., L.G., X.X., Y.X., Y.W.), Nanfang Hospital, Southern Medical University, Guangzhou, China
| |
Collapse
|
164
|
Grondel B, Cramberg M, Greer S, Young BA. The morphology of the suboccipital region in snakes, and the anatomical and functional diversity of the myodural bridge. J Morphol 2021; 283:123-133. [PMID: 34783076 DOI: 10.1002/jmor.21431] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 11/10/2021] [Accepted: 11/13/2021] [Indexed: 12/23/2022]
Abstract
The myodural bridge, that is, skeletal muscle fibers attaching to the cervical dura mater, has been described from a variety of mammals and other amniotes. To test an earlier assumption about the presence of the myodural bridge in snakes, a comparative study was designed using a group of Colubrine snakes. Serial histological sections revealed no evidence of the myodural bridge in any of the snakes examined. Further analyses, including histology, computed tomography (CT), and micro-CT imaging of other distantly related snakes, also turned up no evidence of a myodural bridge. The close apposition of adjacent neural arches in snakes may preclude muscle tendons from passing through the intervertebral joint to reach the spinal dura. It is hypothesized that the myodural bridge functions in the clearance of the cerebrospinal fluid (CSF) by creating episodic CSF pressure pulsations, and that snakes are capable of creating equivalent CSF pressure pulsations through vertebral displacement.
Collapse
Affiliation(s)
- Bryson Grondel
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Michael Cramberg
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Skye Greer
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| | - Bruce A Young
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Kirksville, Missouri, USA
| |
Collapse
|
165
|
Cui J, Xu H, Lehtinen MK. Macrophages on the margin: choroid plexus immune responses. Trends Neurosci 2021; 44:864-875. [PMID: 34312005 PMCID: PMC8551004 DOI: 10.1016/j.tins.2021.07.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/29/2021] [Accepted: 07/01/2021] [Indexed: 12/11/2022]
Abstract
The choroid plexus (ChP), an epithelial bilayer containing a network of mesenchymal, immune, and neuronal cells, forms the blood-cerebrospinal fluid (CSF) barrier (BCSFB). While best recognized for secreting CSF, the ChP is also a hotbed of immune cell activity and can provide circulating peripheral immune cells with passage into the central nervous system (CNS). Here, we review recent studies on ChP immune cells, with a focus on the ontogeny, development, and behaviors of ChP macrophages, the principal resident immune cells of the ChP. We highlight the implications of immune cells for ChP barrier function, CSF cytokines and volume regulation, and their contribution to neurodevelopmental disorders, with possible age-specific features to be elucidated in the future.
Collapse
Affiliation(s)
- Jin Cui
- Department of Pathology, Boston Children's Hospital, Boston, MA, USA
| | - Huixin Xu
- Department of Pathology, Boston Children's Hospital, Boston, MA, USA
| | - Maria K Lehtinen
- Department of Pathology, Boston Children's Hospital, Boston, MA, USA.
| |
Collapse
|
166
|
Abstract
[Figure: see text].
Collapse
Affiliation(s)
- Justin Rustenhoven
- Department of Pathology and Immunology, Washington University in St. Louis, St. Louis, MO 63110, USA
| |
Collapse
|
167
|
Xu K, Jiang X, Ariston Gabriel AN, Li X, Wang Y, Xu S. Evolving Landscape of Long Non-coding RNAs in Cerebrospinal Fluid: A Key Role From Diagnosis to Therapy in Brain Tumors. Front Cell Dev Biol 2021; 9:737670. [PMID: 34692695 PMCID: PMC8529119 DOI: 10.3389/fcell.2021.737670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 08/31/2021] [Indexed: 11/23/2022] Open
Abstract
Long non-coding RNAs (lncRNAs) are a type of non-coding RNAs that act as molecular fingerprints and modulators of many pathophysiological processes, particularly in cancer. Specifically, lncRNAs can be involved in the pathogenesis and progression of brain tumors, affecting stemness/differentiation, replication, invasion, survival, DNA damage response, and chromatin dynamics. Furthermore, the aberrations in the expressions of these transcripts can promote treatment resistance, leading to tumor recurrence. The development of next-generation sequencing technologies and the creation of lncRNA-specific microarrays have boosted the study of lncRNA etiology. Cerebrospinal fluid (CSF) directly mirrors the biological fluid of biochemical processes in the brain. It can be enriched for small molecules, peptides, or proteins released by the neurons of the central nervous system (CNS) or immune cells. Therefore, strategies that identify and target CSF lncRNAs may be attractive as early diagnostic and therapeutic options. In this review, we have reviewed the studies on CSF lncRNAs in the context of brain tumor pathogenesis and progression and discuss their potential as biomarkers and therapeutic targets.
Collapse
Affiliation(s)
- Kanghong Xu
- School of Public Health, Shandong First Medical University and Shandong Academy of Medical Sciences, Taian, China
| | - Xinquan Jiang
- School of Public Health, Shandong First Medical University and Shandong Academy of Medical Sciences, Taian, China
| | | | - Xiaomeng Li
- Department of Hematology, Jining First People's Hospital, Jining, China
| | - Yunshan Wang
- Department of Clinical Laboratory, The Second Hospital of Shandong University, Jinan, China
| | - Shuo Xu
- Department of Neurosurgery, Qilu Hospital of Shandong University and Institute of Brain and Brain-Inspired Science, Shandong University, Jinan, China.,Key Laboratory of Brain Function Remodeling, Qilu Hospital of Shandong University, Jinan, China
| |
Collapse
|
168
|
Brouillard P, Witte MH, Erickson RP, Damstra RJ, Becker C, Quéré I, Vikkula M. Primary lymphoedema. Nat Rev Dis Primers 2021; 7:77. [PMID: 34675250 DOI: 10.1038/s41572-021-00309-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/17/2021] [Indexed: 11/09/2022]
Abstract
Lymphoedema is the swelling of one or several parts of the body owing to lymph accumulation in the extracellular space. It is often chronic, worsens if untreated, predisposes to infections and causes an important reduction in quality of life. Primary lymphoedema (PLE) is thought to result from abnormal development and/or functioning of the lymphatic system, can present in isolation or as part of a syndrome, and can be present at birth or develop later in life. Mutations in numerous genes involved in the initial formation of lymphatic vessels (including valves) as well as in the growth and expansion of the lymphatic system and associated pathways have been identified in syndromic and non-syndromic forms of PLE. Thus, the current hypothesis is that most cases of PLE have a genetic origin, although a causative mutation is identified in only about one-third of affected individuals. Diagnosis relies on clinical presentation, imaging of the structure and functionality of the lymphatics, and in genetic analyses. Management aims at reducing or preventing swelling by compression therapy (with manual drainage, exercise and compressive garments) and, in carefully selected cases, by various surgical techniques. Individuals with PLE often have a reduced quality of life owing to the psychosocial and lifelong management burden associated with their chronic condition. Improved understanding of the underlying genetic origins of PLE will translate into more accurate diagnosis and prognosis and personalized treatment.
Collapse
Affiliation(s)
- Pascal Brouillard
- Human Molecular Genetics, de Duve Institute, University of Louvain, Brussels, Belgium
| | - Marlys H Witte
- Department of Surgery, Neurosurgery, and Pediatrics, University of Arizona College of Medicine, Tucson, AZ, USA
| | - Robert P Erickson
- Department of Pediatrics, University of Arizona College of Medicine, Tucson, AZ, USA
| | - Robert J Damstra
- VASCERN PPL European Reference Centre; Department of Dermatology, Phlebology and Lymphology, Nij Smellinghe Hospital, Drachten, Netherlands
| | | | - Isabelle Quéré
- Department of Vascular Medicine, Centre de référence des Maladies Lymphatiques et Vasculaires Rares, Inserm IDESP, CHU Montpellier, Université de Montpellier, Montpellier, France
| | - Miikka Vikkula
- Human Molecular Genetics, de Duve Institute, University of Louvain, Brussels, Belgium. .,VASCERN VASCA European Reference Centre; Center for Vascular Anomalies, Division of Plastic Surgery, University Clinics Saint-Luc, University of Louvain, Brussels, Belgium. .,Walloon Excellence in Lifesciences and Biotechnology (WELBIO), de Duve Institute, University of Louvain, Brussels, Belgium.
| |
Collapse
|
169
|
Nitz E, Smitka M, Schallner J, Akgün K, Ziemssen T, von der Hagen M, Tüngler V. Serum neurofilament light chain in pediatric spinal muscular atrophy patients and healthy children. Ann Clin Transl Neurol 2021; 8:2013-2024. [PMID: 34482646 PMCID: PMC8528467 DOI: 10.1002/acn3.51449] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Revised: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 11/29/2022] Open
Abstract
Objective The aim of this study was to evaluate neurofilament light chain as blood biomarker for disease activity in children and adolescents with different types of spinal muscular atrophy (SMA) and establish pediatric reference values. Methods We measured neurofilament light chain levels in serum (sNfL) and cerebral spinal fluid (cNfL) of 18 children with SMA and varying numbers of SMN2 copies receiving nusinersen by single‐molecule array (SiMoA) assay and analyzed correlations with baseline characteristics and motor development. Additionally, we examined sNfL in 97 neurologically healthy children. Results Median sNfL levels in treatment‐naïve SMA patients with 2 SMN2 copies are higher than in those with >2 SMN2 copies (P < 0.001) as well as age‐matched controls (P = 0.010) and decline during treatment. The median sNfL concentration of healthy controls is 4.73 pg/mL with no differences in sex (P = 0.486) but age (P < 0.001). In all children with SMA, sNfL levels correlate strongly with cNfL levels (r = 0.7, P < 0.001). In children with SMA and 2 SMN2 copies, sNfL values correlate with motor function (r = –0.6, P = 0.134), in contrast to older SMA children with >2 SMN2 copies (r = –0.1, P = 0.744). Interpretation Reference sNfL values of our large pediatric control cohort may be applied for future studies. Strong correlations between sNfL and cNfL together with motor function suggest that sNfL may be a suitable biomarker for disease activity in children with 2 SMN2 copies and those with >2 SMN2 copies within their initial stages during early childhood.
Collapse
Affiliation(s)
- Elisa Nitz
- Department of Neuropediatrics, Medizinische Fakultät, Technische Universität Dresden, Dresden, Germany
| | - Martin Smitka
- Department of Neuropediatrics, Medizinische Fakultät, Technische Universität Dresden, Dresden, Germany
| | - Jens Schallner
- Department of Neuropediatrics, Medizinische Fakultät, Technische Universität Dresden, Dresden, Germany
| | - Katja Akgün
- Department of Neurology, Center of Clinical Neuroscience, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Tjalf Ziemssen
- Department of Neurology, Center of Clinical Neuroscience, Universitätsklinikum Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Maja von der Hagen
- Department of Neuropediatrics, Medizinische Fakultät, Technische Universität Dresden, Dresden, Germany
| | - Victoria Tüngler
- Department of Neuropediatrics, Medizinische Fakultät, Technische Universität Dresden, Dresden, Germany.,University Center for Rare Diseases, Medizinische Fakultät Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| |
Collapse
|
170
|
Bothwell SW, Omileke D, Hood RJ, Pepperall DG, Azarpeykan S, Patabendige A, Spratt NJ. Altered Cerebrospinal Fluid Clearance and Increased Intracranial Pressure in Rats 18 h After Experimental Cortical Ischaemia. Front Mol Neurosci 2021; 14:712779. [PMID: 34434088 PMCID: PMC8380845 DOI: 10.3389/fnmol.2021.712779] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 07/16/2021] [Indexed: 12/22/2022] Open
Abstract
Oedema-independent intracranial pressure (ICP) rise peaks 20-22-h post-stroke in rats and may explain early neurological deterioration. Cerebrospinal fluid (CSF) volume changes may be involved. Cranial CSF clearance primarily occurs via the cervical lymphatics and movement into the spinal portion of the cranio-spinal compartment. We explored whether impaired CSF clearance at these sites could explain ICP rise after stroke. We recorded ICP at baseline and 18-h post-stroke, when we expect changes contributing to peak ICP to be present. CSF clearance was assessed in rats receiving photothrombotic stroke or sham surgery by intraventricular tracer infusion. Tracer concentration was quantified in the deep cervical lymph nodes ex vivo and tracer transit to the spinal subarachnoid space was imaged in vivo. ICP rose significantly from baseline to 18-h post-stroke in stroke vs. sham rats [median = 5 mmHg, interquartile range (IQR) = 0.1-9.43, n = 12, vs. -0.3 mmHg, IQR = -1.9-1.7, n = 10], p = 0.03. There was a bimodal distribution of rats with and without ICP rise. Tracer in the deep cervical lymph nodes was significantly lower in stroke with ICP rise (0 μg/mL, IQR = 0-0.11) and without ICP rise (0 μg/mL, IQR = 0-4.47) compared with sham rats (4.17 μg/mL, IQR = 0.74-8.51), p = 0.02. ICP rise was inversely correlated with faster CSF transit to the spinal subarachnoid space (R = -0.59, p = 0.006, Spearman's correlation). These data suggest that reduced cranial clearance of CSF via cervical lymphatics may contribute to post-stroke ICP rise, partially compensated via increased spinal CSF outflow.
Collapse
Affiliation(s)
- Steven W Bothwell
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, Newcastle, NSW, Australia
| | - Daniel Omileke
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, Newcastle, NSW, Australia
| | - Rebecca J Hood
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, Newcastle, NSW, Australia
| | - Debbie-Gai Pepperall
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, Newcastle, NSW, Australia
| | - Sara Azarpeykan
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, Newcastle, NSW, Australia
| | - Adjanie Patabendige
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, Newcastle, NSW, Australia.,Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Neil J Spratt
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, Newcastle, NSW, Australia.,Hunter New England Local Health District, Newcastle, NSW, Australia
| |
Collapse
|
171
|
Wafford KA. Aberrant waste disposal in neurodegeneration: why improved sleep could be the solution. CEREBRAL CIRCULATION - COGNITION AND BEHAVIOR 2021; 2:100025. [PMID: 36324713 PMCID: PMC9616228 DOI: 10.1016/j.cccb.2021.100025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 08/11/2021] [Accepted: 08/12/2021] [Indexed: 06/16/2023]
Abstract
Sleep takes up a large percentage of our lives and the full functions of this state are still not understood. However, over the last 10 years a new and important function has emerged as a mediator of brain clearance. Removal of toxic metabolites and proteins from the brain parenchyma generated during waking activity and high levels of synaptic processing is critical to normal brain function and only enabled during deep sleep. Understanding of this process is revealing how impaired sleep contributes an important and likely causative role in the accumulation and aggregation of aberrant proteins such as β-amyloid and phosphorylated tau, as well as inflammation and neuronal damage. We are also beginning to understand how brain slow-wave activity interacts with vascular function allowing the flow of CSF and interstitial fluid to drain into the body's lymphatic system. New methodology is enabling visualization of this process in both animals and humans and is revealing how these processes break down during ageing and disease. With this understanding we can begin to envisage novel therapeutic approaches to the treatment of neurodegeneration, and how reversing sleep impairment in the correct manner may provide a way to slow these processes and improve brain function.
Collapse
Key Words
- AQP4, aquaporin-4
- Alzheimer's disease
- Amyloid
- Aquaporin-4
- Astrocyte
- Aβ, beta amyloid
- BOLD, blood-oxygen level dependent imaging
- CAA, cerebral amyloid angiopathy
- CSF, Cerebrospinal fluid
- Clearance
- EEG, electroencephalography
- EMG, electromyography
- Glymphatic
- ISF, interstitial fluid
- MCI, mild cognitive impairment
- MRI, magnetic resonance imaging
- NOS, nitric oxide synthase
- NREM, non-rapid eye movement
- OSA, obstructive sleep apnea
- PET, positron emission tomography
- REM, rapid-eye movement
- SWA, slow wave activity
- SWS, slow-wave sleep
- Slow-wave sleep
- iNPH, idiopathic normal pressure hydrocephalus
Collapse
|
172
|
Kumar V, Umair Z, Kumar S, Goutam RS, Park S, Kim J. The regulatory roles of motile cilia in CSF circulation and hydrocephalus. Fluids Barriers CNS 2021; 18:31. [PMID: 34233705 PMCID: PMC8261947 DOI: 10.1186/s12987-021-00265-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 06/25/2021] [Indexed: 11/10/2022] Open
Abstract
Background Cerebrospinal fluid (CSF) is an ultra-filtrated colorless brain fluid that circulates within brain spaces like the ventricular cavities, subarachnoid space, and the spine. Its continuous flow serves many primary functions, including nourishment, brain protection, and waste removal. Main body The abnormal accumulation of CSF in brain cavities triggers severe hydrocephalus. Accumulating evidence had indicated that synchronized beats of motile cilia (cilia from multiciliated cells or the ependymal lining in brain ventricles) provide forceful pressure to generate and restrain CSF flow and maintain overall CSF circulation within brain spaces. In humans, the disorders caused by defective primary and/or motile cilia are generally referred to as ciliopathies. The key role of CSF circulation in brain development and its functioning has not been fully elucidated. Conclusions In this review, we briefly discuss the underlying role of motile cilia in CSF circulation and hydrocephalus. We have reviewed cilia and ciliated cells in the brain and the existing evidence for the regulatory role of functional cilia in CSF circulation in the brain. We further discuss the findings obtained for defective cilia and their potential involvement in hydrocephalus. Furthermore, this review will reinforce the idea of motile cilia as master regulators of CSF movements, brain development, and neuronal diseases.
Collapse
Affiliation(s)
- Vijay Kumar
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Gangwon-Do, Chuncheon, 24252, Republic of Korea
| | - Zobia Umair
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Gangwon-Do, Chuncheon, 24252, Republic of Korea.,Department of Molecular Medicine, School of Medicine, Gachon University, Incheon, 21999, Republic of Korea
| | - Shiv Kumar
- School of Psychology and Neuroscience, University of St. Andrews, St. Mary's Quad, South Street. St. Andrews, Fife, KY16 9JP, UK
| | - Ravi Shankar Goutam
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Gangwon-Do, Chuncheon, 24252, Republic of Korea
| | - Soochul Park
- Department of Biological Sciences, Sookmyung Women's University, Seoul, 04310, Republic of Korea
| | - Jaebong Kim
- Department of Biochemistry, Institute of Cell Differentiation and Aging, College of Medicine, Hallym University, Gangwon-Do, Chuncheon, 24252, Republic of Korea.
| |
Collapse
|
173
|
Hsu M, Laaker C, Sandor M, Fabry Z. Neuroinflammation-Driven Lymphangiogenesis in CNS Diseases. Front Cell Neurosci 2021; 15:683676. [PMID: 34248503 PMCID: PMC8261156 DOI: 10.3389/fncel.2021.683676] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 05/05/2021] [Indexed: 11/13/2022] Open
Abstract
The central nervous system (CNS) undergoes immunosurveillance despite the lack of conventional antigen presenting cells and lymphatic vessels in the CNS parenchyma. Additionally, the CNS is bathed in a cerebrospinal fluid (CSF). CSF is continuously produced, and consequently must continuously clear to maintain fluid homeostasis despite the lack of conventional lymphatics. During neuroinflammation, there is often an accumulation of fluid, antigens, and immune cells to affected areas of the brain parenchyma. Failure to effectively drain these factors may result in edema, prolonged immune response, and adverse clinical outcome as observed in conditions including traumatic brain injury, ischemic and hypoxic brain injury, CNS infection, multiple sclerosis (MS), and brain cancer. Consequently, there has been renewed interest surrounding the expansion of lymphatic vessels adjacent to the CNS which are now thought to be central in regulating the drainage of fluid, cells, and waste out of the CNS. These lymphatic vessels, found at the cribriform plate, dorsal dural meninges, base of the brain, and around the spinal cord have each been implicated to have important roles in various CNS diseases. In this review, we discuss the contribution of meningeal lymphatics to these processes during both steady-state conditions and neuroinflammation, as well as discuss some of the many still unknown aspects regarding the role of meningeal lymphatics in neuroinflammation. Specifically, we focus on the observed phenomenon of lymphangiogenesis by a subset of meningeal lymphatics near the cribriform plate during neuroinflammation, and discuss their potential roles in immunosurveillance, fluid clearance, and access to the CSF and CNS compartments. We propose that manipulating CNS lymphatics may be a new therapeutic way to treat CNS infections, stroke, and autoimmunity.
Collapse
Affiliation(s)
- Martin Hsu
- Neuroscience Training Program, University of Wisconsin Madison, Madison, WI, United States
| | - Collin Laaker
- Neuroscience Training Program, University of Wisconsin Madison, Madison, WI, United States
| | - Matyas Sandor
- Department of Pathology and Laboratory Medicine, University of Wisconsin Madison, Madison, WI, United States
| | - Zsuzsanna Fabry
- Department of Pathology and Laboratory Medicine, University of Wisconsin Madison, Madison, WI, United States
| |
Collapse
|
174
|
Zhou J, Guo P, Guo Z, Sun X, Chen Y, Feng H. Fluid metabolic pathways after subarachnoid hemorrhage. J Neurochem 2021; 160:13-33. [PMID: 34160835 DOI: 10.1111/jnc.15458] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/12/2021] [Accepted: 06/20/2021] [Indexed: 01/05/2023]
Abstract
Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating cerebrovascular disease with high mortality and morbidity. In recent years, a large number of studies have focused on the mechanism of early brain injury (EBI) and delayed cerebral ischemia (DCI), including vasospasm, neurotoxicity of hematoma and neuroinflammatory storm, after aSAH. Despite considerable efforts, no novel drugs have significantly improved the prognosis of patients in phase III clinical trials, indicating the need to further re-examine the multifactorial pathophysiological process that occurs after aSAH. The complex pathogenesis is reflected by the destruction of the dynamic balance of the energy metabolism in the nervous system after aSAH, which prevents the maintenance of normal neural function. This review focuses on the fluid metabolic pathways of the central nervous system (CNS), starting with ruptured aneurysms, and discusses the dysfunction of blood circulation, cerebrospinal fluid (CSF) circulation and the glymphatic system during disease progression. It also proposes a hypothesis on the metabolic disorder mechanism and potential therapeutic targets for aSAH patients.
Collapse
Affiliation(s)
- Jiru Zhou
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China.,Department of Neurosurgery and State Key Laboratory of Trauma, Burn and Combined Injury, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Chongqing Key Laboratory of Precision Neuromedicine and Neuroregeneration, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Peiwen Guo
- Department of Neurosurgery and State Key Laboratory of Trauma, Burn and Combined Injury, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Chongqing Key Laboratory of Precision Neuromedicine and Neuroregeneration, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Zongduo Guo
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xiaochuan Sun
- Department of Neurosurgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yujie Chen
- Department of Neurosurgery and State Key Laboratory of Trauma, Burn and Combined Injury, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Chongqing Key Laboratory of Precision Neuromedicine and Neuroregeneration, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| | - Hua Feng
- Department of Neurosurgery and State Key Laboratory of Trauma, Burn and Combined Injury, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China.,Chongqing Key Laboratory of Precision Neuromedicine and Neuroregeneration, Southwest Hospital, Third Military Medical University (Army Medical University), Chongqing, China
| |
Collapse
|
175
|
Cells with Many Talents: Lymphatic Endothelial Cells in the Brain Meninges. Cells 2021; 10:cells10040799. [PMID: 33918497 PMCID: PMC8067019 DOI: 10.3390/cells10040799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/23/2021] [Accepted: 03/26/2021] [Indexed: 12/12/2022] Open
Abstract
The lymphatic system serves key functions in maintaining fluid homeostasis, the uptake of dietary fats in the small intestine, and the trafficking of immune cells. Almost all vascularized peripheral tissues and organs contain lymphatic vessels. The brain parenchyma, however, is considered immune privileged and devoid of lymphatic structures. This contrasts with the notion that the brain is metabolically extremely active, produces large amounts of waste and metabolites that need to be cleared, and is especially sensitive to edema formation. Recently, meningeal lymphatic vessels in mammals and zebrafish have been (re-)discovered, but how they contribute to fluid drainage is still not fully understood. Here, we discuss these meningeal vessel systems as well as a newly described cell population in the zebrafish and mouse meninges. These cells, termed brain lymphatic endothelial cells/Fluorescent Granular Perithelial cells/meningeal mural lymphatic endothelial cells in fish, and Leptomeningeal Lymphatic Endothelial Cells in mice, exhibit remarkable features. They have a typical lymphatic endothelial gene expression signature but do not form vessels and rather constitute a meshwork of single cells, covering the brain surface.
Collapse
|